Wireless communication systems have evolved greatly over the past few years. Current wireless communication systems are capable of transmitting and receiving broadband content such as streaming video and audio. One communication scheme used in today's wireless communication systems is time division duplex (“TDD”). TDD allows for the transmission and reception of data on a single frequency. In a TDD system, communication devices such as base stations and wireless subscriber devices must be synchronized with each other. For example, because the same frequency is used for transmitting and receiving data, if a wireless subscriber device is transmitting while a neighboring device is trying to receive there is potential interference between the two devices. Also, two wireless subscriber devices can be on the edges of adjacent communication cells and be transmitting/receiving from their respective base stations. In this situation either of the base stations receive interfering signals from the other communication cell at similar power levels to the desired transmission.
If one of the base stations in the TDD system loses TX/RX synchronization a stability oscillator at the base station tries to keep the base station in sync with the rest of the system. However, stability oscillators usually only allow a free-run time of hours. One way to mitigate synchronization loss is to equip each site with a stability oscillator, which allows the site to free-run for some amount of time (usually 24-48 hours). One problem with stability oscillators is that they are expensive. Another problem with stability oscillators is that they offer a limited amount of free-run time. In other words, stability oscillators have a maximum drift rate usually measurable by hours before the base station will cause serious problems for the system. If the base station cannot be repaired within the maximum drift rate time, the base station needs to be shut down. In some instances, a repair crew might not be able to reach the base station until well after the maximum drift time of the stability oscillator. Additionally, current solutions for the near/far problem discussed above use a larger frequency reuse pattern. However, this may not be practical for operators with limited spectrum or in dense urban environments comprising numerous small cells.
Therefore a need exists to overcome the problems with the prior art as discussed above.